Mtn Lion and app updates

After installing 10.8 on iMac desktop, unable to download other app updates. Get message: “there was an error at the App Store. Please try again. (null)”. Apple Care unable to resolve. Local Apple Store says clean install would work, but can't yet do because no back up.

SImilar problems? Suggestions? Thanx.

Welcome to Mac-Forums

Recently upgraded to Mountain Lion on my iMac and did a software update AFTER for a couple of applications that I had previously on Lion that I didn't bother upgrading and it went great. No problems at all..

Can you download new apps and only updates are broken? Can you uninstall the apps you are trying to update and do a new installation?

Only updates are “broken”. Hesitate trying to uninstall problem apps until I can do back-up. Hate to lose iPhoto and pic library. iPhoto, Garageband and iMovies are the three in question. the last two arenot of importance to me.

Thanx Ashwin, Wilf